There are two long-range goals of this research proposal: 1. To elucidate the molecular mechanism of ciliary and flagellar motility as well as how these mechanism might relate to other microtubule systems; and 2. to investigate the processes of self-assembly and cell directed assembly of these organelles. The biochemistry an ultrastructure of components isolated from cilia and flagella will be studied with the following specific aims: 1. The proteins comprising the radial spokes, spoke heads and central sheath will be localized within the axoneme by extraction/reconstitution experiments monitored by electron microscopy. 2. These proteins will be characterized and assayed for nucleotide triphosphatase activity and nucleotide triphosphate- or calcium-binding activity. 3. Possible structural interactions between radial spokes, spoke heads and the central pair sheath will be studied by electron microsocpy, optical diffraction, darkfield microscopy and biochemical methods. 4. The 5 proteins associated with the resistant protofibrillar ribbons of doublet microtubules will be further characterized. 5. The role of ribbons and their associated proteins in doublet microtubule assembly will be studied using soluble flagellar and brain tubulin and renatured ribbon proteins.